The present invention generally relates to power protection fuses for electronic circuits and electrical devices. More specifically, the invention relates to one or more embodiments of vertically-connected and temperature-triggered fuse devices that do not require conventional fuse packaging. Furthermore, the invention also relates to one or more embodiments of manufacturing such vertically-connected packageless fuse devices.
Modern electrical devices typically incorporate power-protection fuses to prevent an unexpected and/or undesirable power surge from damaging various components associated with such electrical devices. Many electrical devices operate in environments susceptible to unwanted and dangerous power surges or accidental reverse polarity input connections. If power surges (e.g. a voltage surge, a current surge, or both) are sufficiently high or prolonged beyond a negligible duration, electrical devices subject to power surges can sustain operation failure or permanent damages.
Therefore, protection against power surges have been commonly addressed by conventional power-protection fuses. Some fuses are one-time devices that may need to be replaced when activated, while other fuses are resettable. Regardless of one-time use or resettable characteristics, a conventional power-protection fuse is configured to monitor an operating current and/or an operating voltage of an electrical circuit connected to the conventional power-protection fuse, and is subsequently activated (i.e. blows the fuse to disconnect at least a portion of the electrical circuit, or clamps the operating voltage or current to a lower magnitude), when the operating current and/or the operating voltage exceeds or surges above a defined safe-operation threshold value. Typically, current or voltage surge above the defined safe-operation threshold value may damage, endanger, and/or overheat the electrical circuit connected to the fuse, unless the fuse is activated to disconnect the electrical circuit or to lower the operating voltage or current to a lower magnitude.
Conventional fuses that are often incorporated in integrated circuits (IC's) for power protection include transient voltage suppression (TVS) circuits, which protect IC's from accidental or undesirable high voltage spikes in the IC's. Examples of TVS circuits include electrostatic discharge (ESD) protection diodes. Conventional TVS protection circuits comprise two or more diodes, at least one of which is designed to conduct electricity temporarily in case of a high-voltage surge event. TVS circuits are typically designed to clamp the voltage to a particular voltage value during a power surge event, and are also designed to endure an accompanying current surge through the TVC circuits, thereby protecting the load which comprises integrated circuitry requiring protection from power surges.
However, some dangerous electrical device failures that result in gradual or sudden overheating of an electrical device, which may cause a deadly meltdown or explosion of the electrical device itself, cannot always be properly detected by merely monitoring the device operating voltage or current. For example, a mobile device with a malfunctioning battery or a malfunctioning charger may still exhibit a normal range of operating voltage and current levels, even as the temperature of the malfunctioning battery undergoes a thermal runaway to the point of the device meltdown or explosion. Conventional power-protection fuses that are designed to be triggered based on device voltage and/or current threshold levels alone are thus sometimes inaccurate or inappropriate for safeguarding against certain types of device malfunctions, such as device thermal runaway meltdowns or explosions.
Furthermore, a conventional power-protection fuse is typically encapsulated in a dedicated leadframe package or a cavity package, which takes up an extra space for device integration and also drives up the cost of manufacturing a fuse. In certain types of miniaturized power fuse integration needs, where a minimal fuse footprint and a minimal fuse space occupation in an electronic device is highly desired, conventional power protection fuses encapsulated in conventional bulky fuse packages hamper miniaturizations of power protection circuitry desired by circuit designers.
Moreover, packaging requirements for a conventionally-packaged power-protection fuse typically incur undesirable parasitic resistance caused by wire bonding and/or multiple intermediary elements for connecting electrical circuits to the external and the internal components of the conventionally-packaged power-protection fuse. This undesirable parasitic resistance causes unnecessary power loss through the fuse in a quiescent stage. However, the undesirable parasitic resistance and the related power loss is difficult to reduce in a conventional power-protection fuse, because the fuse packaging components are often inherent and essential for correct electrical connections and operational functionality of the conventional fuse.
Therefore, it may be advantageous to devise a novel electronic component structure as a novel fuse device, which enables small-footprint and packageless connections between the novel fuse device and an electronic device that requires power protection. Furthermore, it may also be advantageous to devise the novel fuse device to avoid the conventional fuse packaging for scalable and cost-effective miniaturization of the novel fuse device incorporated in an electronic device.
Moreover, it may also be advantageous to devise the novel fuse device to reduce or eliminate parasitic resistance inherent in conventional package elements associated with a conventional fuse device. In addition, it may also be advantageous to devise one or more novel device fabrication steps and methods for manufacturing the novel fuse device.